Morgage implications: moving out of my house

galaros25

Any advice appreciated:

I have a mortgage for £63,000 fixed rate (rate fixed for another three years) at 5.5% with Nationwide.

I wish to move into my partner's house, and let my house to my live-in-lodger.

I currently rent out a room for £2200 per year (tax free under rent-a-room).

I would rent the whole house out for £3,850 (but subject to income tax at 22%).

I understand need to tell the mortgage lender if I move out. Will they penalise me? Am I likely to be able to keep the fixed rate term unchanged? Will they charge me some kind of administration fee?

If changing the mortgage situation is complex or expensive then I could choose to keep a room in my house, live in it occaisionally (once a week, once a month, whenever I row with my girlfriend). I would get £803.00 less rent (after tax is considered). but have none of the mortgage/insurance hassle and more storage space. Would this be legal?

I appreciate this is hardly the worst dilemma in the world, but help appreciated.

Thanks in advance