JCVI produced a list of who would qualify for the vaccination. This is the provisional order.
1. Over 80 plus health & care home workers and high risk over 65
2. Over 75
3. Over 70
4. Over 65
5. High & moderate risk under 65
6. Over 60
7. Over 55
8. Over 50
9. Rest of population
The UK has ordered 100 million doses from AstraZeneca/jJenner Institute Oxford Uni so there should be enough to go around (UK population 68 million). They have also ordered 30 million form Pfizer, 60 million from Sanofi/GSK and 60 million from Novavax. Per head of population the UK has ordered more than any other country - hedging their bets that at least one vaccine will come through.
As I am not in the first 3 groups I would take the vaccine when offered as some countries may bar entry to non vaccinated visitors or you have to go into quarantine.