Yes, the NHS app is carrying booster information and the booster roll-out is going very well. We are closing in on 40% of the whole population boosted and that pretty much covers all of those most at risk because all the UK vaccine programs have been strictly by clinical need and age.
Moderna and Pfizer are being used for the boosters and the general thought is that AZ gives really good long term T-cell protection for pretty much any variant and the RNA vaccine as a booster gives good neutralising antibodies.
I suspect that the same will be the case for omicron, it may spread quickly but I think the vulnerable should still be well protected from hospital and death.