DO NOT USE ABs unless a sample has been sent to a Lab because using the incorrect medication encourages bugs to take hold. Get appropriate treatment for vaginal atrophy, it may be that you need to use more than is generally suggested in order to keep the vagina healthy.
ABs should never be used occasionally as they don't do any more than what an over-the-counter pain relief will do. Other than affecting every one of us World Wide when ABs become in-effectual. Do you want to be the one with a serious condition where ABs could save your Life but won't due to over-use ..........
If you have repeated urine infections or are apparently 'prone' to infections then the GP should refer you to the appropriate Consultant. Also, infections are commonly caused by bad toilet hygiene. The bugs usually live in the back passage and are transferred to a totally different environment in the vagina where they take hold. Thrush lives in the back passage too.
VA does mimic urine infection-type symptoms and ABs do help but they should never be used 'as required'. Have a look-see at the threads regarding vaginas and bladders here for advice. Make notes

. Maybe go back to your GP and ask for appropriate referral knowing how long waiting lists are in the UK.
It worries me that even Consultants will suggest reserve supply of ABs

. There is always a reason for infection which the Consultant should investigate!