That’s a daft comment, of course you don’t get arrested in the UK especially if you’re clearly gardening. If you’re carrying a large knife and hatchet in an urban area of France or the UK you are quite rightly going to be of interest to plod or les flics.

Whether or not the police are interested enough to gather their own evidence (collective statements, witness accounts, etc.) and then run with this to the CPS is a non-issue in my opinion.

The OP has already alluded to the fact that he may have the name and address of the vandal in question. If the police are of no help (as they so often are these days) then gather the required evidence and prosecute the individual yourself. This right is afforded to you by the Prosecution of Offences Act (POA) 1985. Naturally, any damages recovered will only account for losses you've sustained that are evidentially provable. It is unlikely that a court (or the CPS if they take the case over) would sustain retrospective charges on the basis of witness statement alone. In law, we say that you must establish a 'prima facie' case. Adding erroneous charges which aren't prima facie may lead the court to assume that the 'information' (charge sheet presented) is motivated by vexation. If you're going to go with this method, you must present the case with candour and your conduct must be unimpeachable, because you're acting as a prosecutor. If you're unsure about anything, you should just instruct a solicitor or barrister---at that point, however, the cost of representation will likely outweigh damages suffered.