Hi Mike,
Looks like i arrived a little too late............lol
As has been said, there are a few decent spots to visit for birding over here. Seaforth Nature Reserve, next to the Liverpool Freeport (in fact its within their grounds) is a very good place to start. There is a warden on the site, who is rather a helpful chap. Excellent for various gulls, although since the development there in recent years gull species seemed to have gone down somewhat. Always the chance of a Med gull. They have been there recently. Little Gulls make an appearance over next few months too. Along with Common, Arctic and Sandwich Terns. At the moment there are also Scaup on the reserve lake, Blackwits, Goldeneye, Grebes and plenty of waterfowl. Over the perimeter fence is Crosby Marine Lake. Thats always worth a visit, as well as the shoreline further up (having had Snow Buntings in December).
I would say the links posted by bill@dwp, especially
http://www.livbird.pwp.blueyonder.co.uk/
are going to prove most useful to you.
A couple of miles out of Liverpool, up the A59, possibly on your route across to Liverpool...is a reserve, in Rufford called Mere Sands Wood:
http://www.westlancsdc.gov.uk/Tourism/index.cfm?ccs=303&cs=738 This is a great place for various Woodpeckers, Treecreepers, various warblers over next few months, waterfowl and a variety of other birds. In the same area, look out too for Martin Mere of the Wildfowl and Wetlands Trust:
http://www.wwt.org.uk/visit/martinmere/
Also worth a visit, specially if you have family with you, is Croxteth Country Park :
http://www.livbird.pwp.blueyonder.co.uk/croxteth.htm
Im not too familiar with the birding sites across the Mersey in the Wirral, but it looks like you have the assistance of Jane Turner to help you there.
All the best,
tracker