Welcome Allan!
Firstly, I am not a T.E. builder, but many of my friends who are have had to farm out the gears, because they are low D.P. and so the teeth are coarse and deep. And for a one or two off, buying cutters is an expensive addition to the hobby. Most of us would rather spend the money on items that we are likely to use more frequently.
Living where you do, I imagine that winter temperatures will be lower than in the south of the mainland, so for what it is worth, make sure that your workshop is very well insulated, and make provision for weatherproof ventilation, with at least one vent close to the floor (water vapour is heavier than air) and another high up, preferably as far away from the low one as possible, to encourage a slight through passage of air. .
Not only for comfort, but to minimise the risk of rust. On this subject, NO combustion heaters (gas / coke etc) that produce water vapour.
here in East Anglis, main heating is a thermostatically controlled 2Kw fan heater during perods of occupation when it is chilly. And under the fitting bench, there is a 60w tubular heater which is left switched on during periods of frost. After 24 hours, a steel bench feels anything but chilly, although but you will not perspire much.
Do ensure that your lathe is level, adjusting the mountings so that there is no twist in the bed, otherwise it will never turn free of taper
Lots of power points, and plenty of lights, on/around the machines and fitting bench, as well as overhead.
Depending on how honest you think your fellow islanders are, be aware of security. Use a 5 lever lock on the door(s), and if the hinge pins are even slightly accessible make/and certainly fit, hinge bolts.
If you have windows, (i haven't, to increase shelf space in a small shop as well as for security) make provision to cover them internally or securely if external).
Do make provision for LOTS of storage. You will accumulate lots of tools, (as well as those that you will make) measuring equipment, and material. If you label the storage for tools, and the tools, especially special purpose ones, you are less likely to pick up something a couple of years later, and wonder what is it is for!
Make sure that the floor is insulated, or that you are insulated from the floor on plastic or rubber mats.
Working when your feet are cold is not much fun! Some time ago, Toys r Us were selling 1 metre sqaures of perforated deep rubber matting for around £16. More now, no doubt, but cut in two, you have two metres of matting to keep your feet warmer, and the swarf falls through the holes so that you have to clean up less frequently (and you don't get ear ache for taking swarf into the house!).
If you use an invertor for speed control, please feed it through a filter. (I have a double socket with a built in filter, but some noise still gets back, (judged by the baby alarm used as an intercom), although without spoiling our radio or TV. Your neighbours on the same phase, even if a long way away, will not be happy to have their Radio or TV spoiled by "dirty" feedback into the mains!
Hope that some of this helps, and have fun! (Once you have a lathe, you will never want to be without one again)
Howard