Does anyone know where I can get the above?

I need two bolts to hold the front mount to the forks & two to hold the rear caliper to the mount!

Any local hardware store, assuming it’s nothing weird/fancy and jsut normal post mount or IS brakes then they’ll just be standard M6 thread bolts of length X, go to local hardware store and pick from grades available, cost pence…

Screwfix/Toolstation do A2 stainless M6 cap-screws in a variety on lengths, you’ll have to buy a box of 50, but will be the cheapest way of buying.

Your local bike shop should also have replacements, if you only want a couple.

Fancy Titanium bolts are available on-line.

Local nuts and bolts store (if you have one).
I have one near me and they will be literally pence.
Last time I went in it cost me 15p for about 5 items.

LBS?

If buying from a fastener supplier check the thread pitch, you can get M6 in coarse and fine threads. Take a bolt with you and try an M6 nut on it
If you buy online try the bolt with fingers only, it should screw in to full-depth easily

It’ll be a 6 x 1.0mm. As above, other thread pitches do exist, but it’s pretty rare to be offered them if you ask for an M6 bolt.