Well I have to say a big thank you to all for your good wishes. I can confirm that Pneumonia is pretty horrible and don't recommend it to anyone! I am now back on to "light duties" and as such have been doing a bit in the Manroom again. Whoop!
One thing I really disliked about Zippy was that half of the fuel tank is held on my screws. My first thought was having a spreader plate with captive nuts, but this is nigh on impossible to achieve due to the area being an enclosed box section. Instead I have gone for a "belt and braces" approach of Rivnuts and epoxy resin. I didn't want them to fall out as the fibreglass is quite thick here, so out came the tank, followed by a bit of drilling. I then applied epoxy resin to the holes and the Rivnuts before fitting them as normal. I doubt they'll go anywhere...
Staying on the subject of fuel, Zippy will be running a Facet Electric Fuel Pump, and I needed to find myself a fuel pressure regulator to keep things as they should be. I found one from an awesome seller on eBay (yes they DO exist!), and once it arrived I just needed to find somewhere to put it. I decided that as there's precious little room under the bonnet, under the wiper motor on the bulkhead would be a perfect place. Some CAD with a Jaffa Cake box saw it replicated from a scrap of steel, and some more quick work with the drill saw all the appropriate holes sorted. A trial fit worked really well, so now it's drying off having been painted. Next job will be sorting some fuel pipes.
Tank out - to sort the fixings
Rivnut trial fitted before adding epoxy resin
Fuel Pressure Regulator - I need to put this somewhere
Bracket concocted from scrap steel
Trial fit - looking good. Bracket now in paint.