If you want to buy on line try this link.
They sell four categories of chart as listed.
1. Cancelled @ £3.05
2. Second hand not up to date @ £8.25
3. Second hand and up to date at date of purchase @ £11.35
4. New @ £18.95
There are Three charts listed that may be of interest to you.
No 2010 Morecambe Bay and Approaches
No 1320 Fleetwood to Douglas
No 1552 Ports in Morecambe Bay, River Lune and Approaches to Fleetwood, Heysham and Glasson.
Don't know your area very well but sure there must be something of interest, they also buy charts if you have got any to dispose of.