Biggles, there may be no shortage of applicants for pilot but the need for quality applicants continues. I don't have the 08/09 figures to hand but I expect it will be similarly large to 07/08.
If you have the qualities required for officer but also those for pilot it will be pilot that you will be offered first.
Which service?
The Army may fly more helicopters than the RAF or RN but I do not believe they offer the best opportunities.
The Navy naturally offer the chance of sailing to foreign parts but many aviating in the Navy wear light blue uniforms.
For the RAF OTOH flying is their core business. They operate a greater range of types in more roles than the others.
Certainly if you want to fly attack helicopters - Fly Army.
If you want to fly Harriers, but more likely helicopters - Fly Navy.
If you want to fly fast jets, transports, helicopters or even trainers, well work it out.