Just an update...
We did decide in favour of a side door, which was built for us as a 'self-fit' by Martin Kedian and we are highly delighted with the results.
The kit came as a primed and (oak)lined unit with fixings requiring only the enlargement of the existing window opening to the pre-agreed size and some drilling for the self-tap fixings from the frame flange into the cabin sides.
I had wimped out of using an angle grinder for the cuts as I have polystyrene insulation and the fire risk was unacceptable. Also I had been assured by boaters that a jigsaw would work fine if I was happy to take it slowly. Well, I usually pride myself on an unnatural level of patience, but having spent all morning and several packs of quality metal blades to make a cut of about 8 inches I went home to find my Bosch reciprocating saw. This completed the cuts in about 20 mins at the cost of just one blade (probably my fault). The unit was siliconed and ST screwed in place in a further hour and all the rest of the time was tidying the inner lining and adding some trims.
Must say the finished job has brought much interest and many compliments from boaters here at Pillings Lock. I should have got an 'introduction agreement' out of Martin Kedian.
Without one, at least I don't feel guilty about saying Martin's fabrication was faultless and the oak lining is beautifully crafted solid oak, the guy really is a craftsman and understands exactly what is required. This is not a 'cheap and cheerful jobbie', but it is the quality most of us would want and expect at a reasonable price for a made-to-measure item, and one you can be proud of.
Pete and Pat