In reply to KingStapo:
I've knocked walls down in my own house but have a background in engineering so was very confident about the assessment I made about load bearing. This is easy stuff to do if you understand how buildings are put together. If not a good builder should be sufficient or use structural engineer (search "find an engineer .com"). Write a brief scope of work for a builder and include responsibility for assessing structural aspects.
Either way - I would contact your local building control office with a description of what you intend to do and a simple sketch showing plan of rooms and any structure above. In my case they responded in writing stating work was outside scope of building regulations. Nice to have this when you sell the house. They are generally very helpful.
There is a remote possibility that different regulations apply as well as structure, e.g. fire, thermal efficiency (if you remove render from walls). Also you need to consider if the wall is acting as a stiffener for the adjacent walls (if they are long runs).
SDS drills and kango hammers are great, but they can loosen surrounding brickwork very easily, care is needed around the bits you want to keep.
Depending on the competency and level of making good (e.g. levelling up to floor, plastering the 'gap', removing spoil) £400 could be a good price. I assume £150-£200 a day for a reasonable builder + materials.
I'd recommend a roll of polythene to seal up doors and the gap into the loft (dust in lofts/insulation is impossible to remove but will re-enter the builder as dirt later).
ps - building projects can be addictive...
