WITH 100 days to go to the Olympic opening ceremony, the dream of a lifetime is crystalising towards reality for some.

But others have already awoken to their worst nightmare: the knowledge that all that sacrifice, investment, and aspiration have been in vain.

David Florence, who won C1 (canoe slalom) silver in Beijing, has earned the right to challenge for two golds this time. He was one of five paddlers nominated to the BOA after the slalom trials concluded last weekend on the Olympic course at Lee Valley. The 29-year-old Florence will also team up with Richard Hounslow in the C2.

Hounslow ended the hopes of an Athens silver-medal Scot, Campbell Walsh, beating him in the one-man kayak. Another Scot whose campaign ended there was 2008 Olympian Fiona Pennie in the K1. Mistakes in the trials must have been paticularly hard to bear, given that both Scots had been quickest on the water in training. At 34 and 29 respectively, this may provoke consideration of retirement.

However, new qualifying rules mean a second C2 crew has qualified, with Aberdeen's Tim Baillie also nominated. The Olympic canoe squad will be up to 17 strong, but no further Scots are in contention. Already it seems the overall Scottish contingent in Team GB may number nearer 40 than the optimistic 50 which was touted.

Among 38 swimmers already selected are five Scots: Hannah Miley, Robbie Renwick, Michael Jamieson, Craig Benson and Caitlin McClatchey. It was a dream come true for 17-year-old Warrender swimmer Benson, the world junior 100m breaststroke champion and record holder, who now holds the Scottish record once held by 1976 Olympic champion David Wilkie.

The GB swimming squad expects to make around six further nominations.

Andy Murray has chances in tennis, but quadruple Olympic cycling champion Sir Chris Hoy and triple Olympic rowing silver medallist Katherine Grainger seem Scotland's best medal hopes.

Murray could play three events, but so intense is UK competition in cycling – and only one per event can be nominated – that Hoy has no guarantees. Jason Kenny upstaged him in the sprint at the World Championships, and there were those ready to write off Hoy, but the Edinburgh rider confounded his critics by then claiming keirin gold, having already ridden the team sprint in which Britain were disqualified. The Hoy v Kenny – defending Olympic silver medallist – sprint debate remains.

Hoy has also had to overcome fellow Scot Ross Edgar to book his keirin place. Edgar was runner-up to Hoy in Beijing, and also had his sights on the team sprint for London, but the defection of German rider Philip Hindes to GB colours means Edgar has now only a remote chance of making it into the 2012 team. The danger is that it prompts his premature retirement before Glasgow 2014. David Millar may yet supplement the cycling contingent if the BOA lose their doping battle in the Court of Arbitration for Sport.

Grainger seems the UK's best Olympic rowing medal hope, with Anna Watkins in the double sculls. The Glasgow-born Grainger has six world titles and three silvers, making her the first British female Olympian to win medals in three successive games. Missing gold for a fourth time would be the cruellest of fates, and she is unequivocal about London and the lure of gold at a home games having kept her in the sport. Anything less would spoil her dream.

Two more Scots have a chance of rowing selection: Heather Stanning and Lindsey Maguire – one-time Scottish athletics internationalist, sister of former Scottish pole vault record-holder Kirsty.

In badminton, prospects look significantly better than a year ago. Susan Eglestaff has thus far got the measure of arch rival Liz Cann, who halted her at the Commonwealth games in Delhi, while in the mixed doubles Imogen Bankier and her English partner Chris Adcock are front-runners ahead of England's Nathan Robertson and Jenny Wallwork. The British mixed rivals are this week seeded to meet in the quarter-finals of the European Championships in Sweden.

Not one Scottish track and field competitor can be regarded as a banker for selection, though Lee McConnell (400m) and one-lap hurdler Eilidh Child are among those who should make it. Anything more than four athletes would be something of a triumph.

Paula Radcliffe was selected for the marathon back in December, but recent form suggests she will be no more than a bit player. Recurring injuries and recent pleurisy have caught up with the world record-holder and rendered her mortal. She completed a course of antibiotics just a day before the Vienna half-marathon last weekend, and it's a moot point whether this was ill-advised – possibly compromising her health, and for what? She clocked 72min 03sec in her first attempt at the half in three years. It was her slowest time by some two and a half minutes, and one which 10 UK athletes have bettered in the past five years.

Radcliffe and Mara Yamauchi are already nominated for the Olympic marathon, leaving only one women's place up for grabs this weekend in the Virgin London Marathon.

Among those with a chance of the remaining place are Scotland's Susan Partridge and Freya Murray, currently ranked first (71:34) and third (72:32) in the UK over the half this year. However, some 10 women have run inside the qualifying standard. To make the team, either Scot would have to go significantly under 2:30.

In hindsight, selecting so far in advance may well be counterproductive. It's not as if Radcliffe, for all her prodigy, has an Olympic success record. She has undoubtedly been worth Olympic marathon gold on her career stats, but would surely now gladly settle for a competitive run in London on August 5, never mind a medal of any colour.

Some Olympic dreams are fading fast, and many a tear will fall, even before the flame is lit.