I blew the top off my rad once, and as testament to the bonnet vents, it dumped 5 litres of water onto the windscreen in less than a second
dont use any eggs, sealer or any kind of rad-weld product unless its just to get you home in an emergency. They work by coating the inside of the rad with a film that unfortunately decreases the efficiency.
if your going to get a standard replacement rad, try and get a UK Sunny one and not a Pulsar, the UK Sunny one is the same price but it around 0.5 inch thicker and more efficient.
I think your best bet is just to go and source an aftermarket one locally, the price you would pay to ship in a standard UK one is a lot more than getting a custom one made...