I would urge you to contact the Pensions advisory service, for the cost of a local call they provide free professional advice on pensions and the best updated advice on when / where to buy annuities. It could save you ££££'s.
Recent reports suggested that in the current climate of the credit crisis, it was a relatively good time to purchase an annuity. Speak to TPAS below, they are experts on this subject.
http://www.pensionsadvisoryservice.org.uk/