We are in Cheshire (Northwich) so can offer you some ideas which may be of help.
I too would recommend Dee SC for both cruising and racing. It is very tidal though – several knots of tide can be a bit off-putting plus you are restricted to around 3 hrs sailing over high water so you may want to build up a bit of experience first.
There are several good inland locations closeby that we use from time to time which would be all good for learning.
Manley Mere (nr Chester)
Tatton Mere (Tatton Park, Knutsford)
We’ve also launched at Northwich Marina for a river trip on the Weaver.
In terms of coastal sailing West Kirby is good for a trip out round the Hilbre Islands. Wallasey is an option for getting out on the Mersey (we’ve not done that yet but it’s on our list).
Looking a bit further afield to North Wales there aren’t a great number of good launch sites along the coast until you get to Anglesey. Menai Bridge and Beaumaris in The Straits are worth considering. Bala is excellent for some lake sailing.
I’ll send you a pm with my contact details – feel free to get in touch.