Im going to buy a soldering iron and have a go scratch building masts. What should I look for in a iron?
I've seen several with wattage as low as 12 going up to 80 watts. What am I likely to need ?
I guess the finest tip I can find would be best. too?

Any advice appreciated

You want something with a very small tip. I have seen an interesting one advertised in the US that doesn't require a lot of Heat -up time, but can't help uyou much there.I can't see a need for high wattage and all that as what you are dong is not stress related and shouldn't need a heavy duty solder