Are you aware that building a 'L' shape extension will need planning permission first, this will set you back another 3-4 months. Plus Building Regs would need reapplying for. Also, from my experience conservatories only need building regs approval if they are over 30sqm; which means most conservatories are shoddy built and the foundations are unlikely to be suitable for the transformation into a proper extension. Also, the floor is unlikely to have been insulated - sorry but conservatories can be a hornets nest of problems. My advice is yes you should have a door off the hallway into the new room, cost of that should be minimal as you are only looking at using a couple of standard concrete lintels which are cheap as chips! Although I would have put the shower room at the front as the current layout means friends and visitors end up going through your kitchen to use the convenience. It has the advantage the new reception room as a rear garden outlook. Hope that helps

@rinked Thanks, good idea - i'll see what it looks like later. @Suzanne C thank you for sharing your experience and pictures. We'll be going out for quotations once our planning is granted so i'll make sure i get a cost for wet UFH. I think it would be the preferred route with the warmth underfloor and extra wall space is always good in open plan extensions. @minipie Thank you. The software really is great once you get to grips with it. We've started to obtain budget costs on the roof lights and one company has offered to take us to see a few recently completed projects which should hopefully give us some inspiration and allow us to gain some feedback from previous clients. I'll aim to get at least one opening roof light after all the advice received on this board. Thank you for sharing your experience. I'll look into the small radiator in the bathroom. Good idea. The extract routes are pretty easy as the kitchen hood is on an external wall, as is the utility. The WC fan will follow the existing route above the utility rooms ceiling. Not sure on the subfloor as not taken up any flooring so far but the house was built around 2003 so you'd expect a pretty thick solid concrete slab so it might not be as easy as excavating in an older property.

Because things are slowing down in general and we keep getting this recession word thrown into conversations people are becoming wary of spending so they’re not placing orders which is why builders are more readily available. We are contractors and have just started to notice a drop in orders therefore start times will be quicker but having said that we would still be a minimum of 2 months as opposed to our normal 4 months. Just vet your builder if he can start immediately to ensure his work is good. l presume he/she is a recommendation or you have used them in the past. l’m always cautious of contractors who can start immediately. l don’t think prices will go down for some time yet.

Thanks for your comment. On the side extension. We have side access down the right of the house and next to that a detached single garage. This is not shown in position and touches against the neighbours extended house. We have considered a side extension but thought the knocking down of the garage and side extension might be more expensive than a rear extension. There is also a drain down the access way which might need to move. Our garden is a fair size and even with a side extension we could plan this not to lose side access. For the Utility room our kitchen doesn't have enough room our tumble dryer is with a relative and we have items still in the Garage - brooms, cleaning things etc since our move a few years ago. I am still going to the garage to access these items. On moving downstairs things upstairs. Our boiler is in the loft. For the washing machine I dont think I would move it. We are using all the bedrooms between ourselves, our two children, guest room for family or as an office. I was until very recently working full time from home and likely could again. My husband and I still work in the office some days each week. I appreciate these comments and will add some details to my original post.