Hi IndyB
I think it depends how bespoke you want to be. There are pros and cons to all routes, but let me summarize:
1. Bring several independent parties to the table yourself. So employ an architect, structural engineer, party wall surveyor, building regs and CDM company for the pre build phase and then employ a build team / project manager. Given your self confessed lack of experience, this may be unwise, but it is an option.
2. Go with an "all in" design and build team. There are some excellent operations in the area. Costs can vary significantly and as with everything you get what you pay for. The great thing about this option is you have everything under one roof and ultimately they are responsible for the whole project so there is no cop out from them. Issues can be that you don't know the quality of the professional services they are bringing in as they will be in house so while you may think you are getting a very experienced architect, it may only be a very junior cad designer. I guess this shouldn't be an issue if you like the designs, but there is so much more to a plan than just how it looks, it also needs to work! As I say though, most operations out there are very proficient. As a previous poster has mentioned the best way to make sure they will deliver is to speak to previous clients and go and see work they have done. On insurance this is vital also, in the unlikely event something does go wrong. The builder will probably show you insurance docs (if not you must ask for them) but then it is difficult for you to know if the cover is sufficient. If you want to pm me I can put you in touch with a construction insurance consultant who can advise you - I use him a lot.
3. Work with an architect to take you through the whole process. If you want a very design led approach this may be the way forward for you. Architects vary in price dramatically and once again you get what you pay for. Once you have appointed one you are pretty much committed to them and there is nothing wrong with that, but one thing you should be aware of is that they actually own the designs they come up with, even if you have paid for them. So if you change architect during the process, you will have to come to an arrangement for the next architect to take on the same drawings. That said this is very much the traditional approach to building works. Architects will advise on all areas and will bring in all required professionals and even build teams (either their recommendations or your own). As I say this is very much the traditional route and a tried and tested one, but may not be for everyone.
4. Marketing "front" companies. You will know these as some loft / extension companies. There are lots around and again they are 'horses for courses'. They deliver pretty well on the whole, there are always exceptions, but while you think you are employing them directly, if you look at the contracts you are actually paying them to put in a subcontractor who is responsible for the work. They take their payment from you but don't actually have responsibility for the work. If the budget is tight, they tend to be the option people go for, but just beware who is responsible for any problems.
5. This is where I have to confess a vested interest. I hope you think what I have written above is a help and I am not going to sell our business. We offer something different to the above but rather than push, I'd invite you to have a look at our website -
http://www.goodlondonbuilders.com.
All the options above are valid, it really depends on what you want and how you want to approach it.
If you would like more advice I'd be happy to answer any questions and I promise to stay as impartial!
Cheers
Rory
MD Good London Builders