The Reid wrote:

yes! (something to note if I upgrade shower, never realised they
are 9 now!!! )

The highest powered ones are about 10.8 kW (needs 10 mm^2 cable).

1. What is the view on a ring main junction box for a spur
mounted on the wall near the fusebox rather than under the floor
(i need to free up the fuse the freezer is using) I really don't
fancy ripping up the floor to add a spur,

Either of those positions would be OK, but why not just wire the spur
into the fuse box? There's nothing to stop you taking a spur from the
origin of the circuit, in fact it's a better way.

2. Fuse holders. My Wylex fusebox has fuse-wire fuses (25 years
old) I tried to get a green coloured one for the cooker position
(perfectionist, me :-)) , the one I bought in a DIY shed turns
out to not fit Do people reckon I'll find one that fits in a
better shop?

Green is 45 A and won't fit the older Wylex boxes, as you've just
discovered. 30 A (red) one should be OK for your cooker circuit. If
you really need a 45 A circuit you'll have to get a separate 1-way Wylex
box and split the meter tails using service connector block (Henley block).

Individual domestic cooker circuits don't have to be rated for the full
appliance load, as the probability of having all the rings and things on
at once is tantamount to zero. You're allowed to use the same diversity
rule that I mentioned before - so if it's a 12 kW cooker the circuit
design current is 23 A and a 30 A fuse is quite OK. 6 mm^2 cable is
usual, but check the grouping and other derating factors to be sure.

--
Andy