As ETOPS has said, Merseyflight at Hawarden/Chester is your nearest and most convenient school. You also have a choice of schools at Liverpool and Barton which would be reachable within an hour. You could also head south to Sleap which has an excellent flying club but is a bit of a hike by road from Frodsham.
If you're only in the UK for six months you should be able to use your Kenyan licence for a temporary period. Speak to your chosen school and check the information on this page:
Recognition of ICAO third country licences in UK airspace Guidance for licence holders