I thought I’d look into this in a bit more detail. The EU population is 446 million, with 27.9% over 65 according to Wikipedia, so there are approximately 160 million of them. The UK has vaccinated 31m over 50s with one dose, of which 2.8m have had two doses so far. The % fully vaccinated in the UK is similar to France, Germany and Italy at about 4% of the population. There is a disparity in vaccine supply due to the different contractual arrangements, but in reality if UK had not vaccinated anybody and all those doses had gone to the EU, it would still be a drop in the ocean in terms of the EU requirements (15.5m more people over 65 across the EU approx would be fully vaccinated).
The supply problem for the EU is much greater than the fact that the UK negotiated better contracts with the suppliers, as we are small fry compared to their needs. Knowing this doesn’t help the population of the EU get vaccinated quicker, it’s a very sad situation.