Visas

Singapore
No visa required - need ticket out
Malaysia
No visa required - need ticket out 
Thailand
No visa required for less than 15 days if arriving overland - need ticket out
Cambodia
Apply for "e-visa" no more than 3 months before - enter 17th May, earliest I can get visa 14th Feb, possibly get visa at border, Poipet.
Laos
No more than 2 months before. Possibly get one at border - 15 days USD20.
China
No more than 3 months before - enter 4th June, earliest I can get visa 4th March.
Kyrgyzstan
Hopefully can obtain one on arrival, you can get one at the airport. £60 1 month. All nationals (except nationals of the UK) are required to register with the department for visas and registration within three days of arrivals, hotels will normally carry out this service for their guests.
Kazakhstan
Can get one there? Or from London? £35
Uzbekistan
Very painful.
Turkmenistan
Organised by tour company?
Iran
Nationals of Israel or holders of passports containing a visa for Israel (either valid or expired) will be refused entry under all circumstances. Women judged to be dressed immodestly will be refused entry.
Women over nine years old should wear a headscarf in their visa application photo in accordance with Islamic custom.
No more than 90 days before - enter 23rd August, earliest I can get visa 23rd May. Can take 4 weeks to process.
Turkey
Available on arrival. £10 for 90 day, multi-entry vias
Greece (Crete)
Some Schengen Convention thing
Croatia
No visa is required for stays of up to 90 days
Italy
Some Schengen Convention thing
Germany
Some Schengen Convention thing
France
Some Schengen Convention thing
England
Possibly that Ancestry visa thing.
Scotland
Possibly that Ancestry visa thing.