Assuming your Triban has a 30/40/50T chainset, 12-25 cassette and the RD2300 rear mech currently as standard, then the issues are a) whether you really want/need a cassette that goes to 30T (it will give you a 1:1 drive) which some would say low enough to go up walls, and b) whether the 30T can definitely be accommodated by your existing rear mech.
To deal with the second issue, the
RD2300 seems to have an official 26T max cog size limit and wrap range of 35T. So a 30T sprocket in a 11-30T cassette is exceeding official max cog size by 4T, and wrap capacity by (50-30+30-11) - 35 also 4T. There is a good chance the rear mech can handle it, but without trying it I would not like to guarantee it. You can check the actual max cog size limit by measuring the clearance between top jockey wheel and the 25T sprocket when you are in that gear - if it is definitely more than 10mm then max cog size is not going to be a problem. Checking the wrap range is a little more tricky - you would need to assess whether the rear mech can readily retain tension (i.e. not allowing it to go slack when you are on small front and back) with a chain that is at least two links (a pair) longer than the current minimum - likely in my view, but again can't guarantee it.
I might be misreading your post but it is certainly a challenge sourcing new "road" cassettes as cheaply as mtb (i.e. wider ranged) cassettes. But we are where we are. So if you want compatibility certainty then one such as the HG51 12-25
here is a safe choice for a few £s more.
If I were you I would get a KMC or sram, not Shimano, 8 speed chain - you can easily get one for just a few £s.
