What is the part number for these forks?
Essentially - yes! I too tried to get away with just swapping the forks but came to realise it's unfortunately not as cheap and simple as that- there will be several yoke assemblies to choose from on ebay, tbh you're looking at another £50, if you're keen on doing this I'd send several of the sellers questions asking what deal they'd do for the set of yokes and spindle, possibly the wheel (wheel isn't necessary now, you can use the fazer one and get a wheel later)
If you plan on keeping the bike for a while then yes, it's worth the money. The next lofo ride out should be 5th July, if we can both make it you're more than welcome to swap bikes for a bit during the day so you can see the difference for yourself!