I think i'd find out from the local council about any wants and wishes they might have and any restrictions. I don't think that massively grand plans are warranted on this type of property. Yes, of course you want it to look nice, but just because some things are possible, doesn't make them a good idea every time, and everyone has a budget, Radically changing the exterior in this case needs to be kept in the realms of realistic for the style and situ of the property and end re-sale price plus type of purchase likely to buy. Going ultra modern and pie in the sky with ideas is a waste of money most probably. Grey windows do not in my opinion sit well with red brick for instance or a brown roof. You could render then whole facade in a colour of your choice or paint the bricks to darken down with iron oxide and make them sit better with Grey. The driveway needs an uplift and you'd have to address the finish and colour of the wall to the perimeter to match. A pitched roof to tie in would also, in my opinion look better.

Floor plan:http://media.rightmove.co.uk/56k/55208/41241522/55208_UKB0696_FLP_04_0000.jpg Sorry can't add dimensions but as follows. LOUNGE/DINER: 'L'Shaped 5.86m x 4.05m (19' 2" x 13' 3") narrowing to 2.7m (8' 10") (or Lounge Area 4.05m x 3.14m (13' 3" x 10' 3"), Dining Area 2.72m x 2.7m (8' 11" x 8' 10"). SITTING ROOM: 5.86m x 2.71m (19' 2" x 8' 10"). KITCHEN: 3.2m x 2.54m (10' 5" x 8' 3"). Enclosed side UTILITY PASSAGE: 5.78m x 2.22 (19' x 7' 3") narrowing to 0.95m (3' 1"). MASTER BEDROOM SUITE: 3.83m x 3.01m (12' 6" x 9' 10"). SHOWER ROOM: 3.02m x 2.8m (9' 10" x 9' 2") (originally bedroom 2) FRONT BEDROOM 2: 2.87m x 2.24m (.285' 5" x 7' 4"). CLOAKROOM: 1.79m x 1.77m (5' 10" x 5' 9")

I think you have enough space, but I'm not sure you're gaining much with this plan. Or anything, actually. Count the base units you currently have, and compare against what you would have in the new plan. I would forget about extending the wall (shown in red) and I would instead extend the counter to that point, gaining what looks to be about 1m of useable worktop and undercounter storage. I'd make this peninsula at least 800mm wide, and put your banquette seating backing on, with your table parallel to peninsula. I think you also have room for shallow-depth cupboards on the kitchen wall I'd think very carefully before removing the downstairs loo. This would be a dealbreaker for many potential buyers in the future, if you ever want to sell.

How many people use the bathroom and toilet? Keeping the toilet separate will avoid morning queueing.  There were five, often six people in our house, we kept ours separate and had a small handbasin fitted in the toilet too.