Word of mouth is a good place to start.
One thing I would say is that don't rely 100per cent on an IFA or planner, take time to educate yourself.
There are lots of ways to cut up the pensions pie, so have a think about what your lifestyle aims are and be very mindful of investment charges (including you r adviser's charges).
I am no expert by any means, but know a lot more now than I did a few years ago.
First of all, find out what sort of pensions you have and where they are invested, look at sites like Money Magpie, Money Saving Expert and have a free consultation with the government's Pension Wise service (pensionwise.gov.uk) before you see an adviser.
In my experience (and I found this out the hard and expensive way), some advisers (even if regulated ) are ultimately driven by the commission they will make rather than treating you holistically. I haven't had experience of financial planners though and that might be a better option for you - someone who can look at your whole situation not just investments.
There's a very good podcast called Retirement Answers Man too - it's American, so don't use it for financial and pensions planning, but there's lots of great advice about how to approach this stage of life.