Approaching local venues advice

Hey folks! UK-based engineer here hitting a bit of a brick wall trying to get beyond being house FOH for a couple of local 200-cap-ish venues.

Obviously I realise the quickest way to get into new venues is always networking, but in the absence of personal or professional connections, how would you approach emailing venues (cold) to enquire about any work opportunities? The ones I've sent out so far either get ghosted or I get a "we'll keep you on file for the future" which is never followed up on.

Any advice welcome! Cheers