Duncan, your size is going to be against you. You could try Wicor Marine
at the top end of Portsmouth Harbour, they have a substantial jetty to lean against. Possibly Duver Marina in Bembridge depending on your draft
. Lymington Town Quay is another booked through the harbourmaster I think, chandlers over look the quay which could be useful. Saxon Wharf on the Itchen has a superb wide slip but needs a recce before hand so you land on the flat bit. Concrete wharf to lean against. Crosshouse Hard under the Itchen Bridge is another and free, but avoid when southampton
are playing at home or you will never park in the area.
Used to be a small boatyard next to Marchwood Military Port, a possibility. Itchenor has scrubbing posts and a hard gavel base but not sure they would take your size.