if you have a number of items with two-pin plugs, it is important that all your sockets are RCD-protected. A recent build will be, a reasonably modern house can have RCBOs fitted on the socket circuits at reasonable cost by a qualified electrician.
Electrical sockets often have single-pole switching (i.e. they turn off only the Live wire and leave the Neutral connected. Appliances with two-pin sockets may have no way of determining polarity. I will have to think about the significance of this with your appliances. For example I see that leading brands like MK, Crabtree and MEM offer DP switched sockets, but budget brands like BG and Marbo offer SP. There might be other ranges in the same brand that are different.
Appliances with the wonderful BS1363 plug should always have the L wire (usually brown) connected to the L pin, and fused. 2-pin plugs don't work that way, because they usually fit either way up. I don't know if you will find a brown and a blue wire in your flex, or if it will matter, because it doesn't usually come up.
You can buy plugs and cartridge fuses in quantity here. The tough plugs are unlikely to crack if dropped on, for example, a concrete or tiled floor. I am suspicious of budget-priced plugs. You do not need, and should not use, "covers" or "blanks" as they interfere with the safety shutters in our wonderful BS1363 sockets
you can calculate the Amperage of fuse required by dividing the Watts of the appliance by 240 (UK is actually on 240volts so your kettle will boil slightly faster than in other parts of Europe).
So 3000W (3kW) is 3000/240=12.5 so use a 13A (brown) fuse
A 20W table lamp is 20/240=0.08 but a 3A (red) fuse is the nearest in common use.
3A, 5A and 13A are the only ones generally used. A TV might be 5A (black). Plugs are often made with a little window so you can turn them over and see the colour of the cartridge without unscrewing the plug.