An email in from a buddy who has managed quite a few commercial and larger (multi dwelling) building projects:
The only other things to be aware of and concerned by is the type of building contract to be used. The standard form JCT contracts, I believe, are biased towards the contactor, the ACA standard form was written by Architects and is more balanced.
You also need to think about the level of damages for overrun on the contract. This is slightly more complicated than it might appear. One of the most crucial decisions made by the contract administrator is the issue of the Practical Completion Certificate as this signals the contract has been satisfied.
If there is an overrun, as invariably there is, he has to decide who is at fault and you are in the territory of the famed “critical path”, ie if the delay prevents progress on the rest of the build its on the critical path and who ever caused that delay in culpable. The reason these decisions are important, even for one week is there is a swing for every week by approximately twice the level of damages assuming damages are set at a level similar to the “preliminaries” figure. Prelims are the costs to the contractor of being on site, ie his admin costs. So if damages are say £2000 pw and prelims say £1500pw and there is just one week delay caused by the contractor he is £3500 down. You get the picture it can get very prickly.
Good luck, I am sure it will go well, new builds tend to be easier, provided they are well planned, because there are less unknowns. Keep an eye on any unusual materials and/or bespoke items that have long delivery lead in times and/or are coming from none standard sources as these can be the source of serious delays.