This is a tough one to comment on just based on these drawings. What caught my eye though was that you need a proper corridor through to the new extension. A room that becomes a corridor is always wasted and not an enjoyable space to spend time. I would also be a little worried about the location of your utility. It might make more sense to relocate that utility to next to the new kitchen and turn the existing utility space into an ensuite for the bedroom you are putting where the kitchen used to be.

Thank you so much. Utility to WC is a great idea. We had thought about a corridor and it’s not ruled out, but it would make one or both of the rooms on that end a bit narrow. ive attached a better photo with measurements.x

I am pretty sure you would be best off taking the corridor out of Bed 2 and then with the room that is left make that your new utility. That way you retain your current Bed 1 as a nice room rather than turning it into a corridor.

Another option you may not have considered is moving the front door. Tough to say if it's a good idea without being at the site. But it may give you some interesting options with the layout of the existing space.

I’d be looking at combining and reconfiguring that bloack consisting of the current wc, kitchen, utility, garage and that space behind the garage into the open plan kitchen/diner plus living area to take advantage of the south facing aspect - this is where all the services are located at the moment. The small front bedroom could be split into a new bathroom (+ small ensuite?) with a corridor through to a new master bedroom & further bedroom. Is the front garden private enough for you to have a small patio also?

Hi Kate Fewster, as you have spoken about extending your home then you may find our blog interesting. It is all about mistakes to avoid which you may find an interesting and helpful read. I have linked this below for you. https://www.thelivinghouse.co.uk/blog-interior-design-tips/the-6-most-common-mistakes-we-see-when-you-extend-your-home