If you have a car made in 2024 or 2025 it won't be a good idea to leave the car parked up, locked up with alarm on for 4 weeks same for a 2022 made car but possibly less so. It also depends on how high or low instate of charge the battery is when you first parked it up as it will only get lower so a lower start point means a lower end point. The battery likes about 20C and starts to discharge itself more at higher temperatures. Plenty on threads on this site alone about flat batteries from cars being parked up and all the unexpected warning lights and messages, unseen error codes and issues from the battery being low but the headlights still seem bright enough and the engine starts. The computer systems and programs don't like the battery in too lower state for them (plenty of threads on the site exampling this). Best on to (get someone to) connect the battery to an appropriate charger maintainer following the instructions in the car's 'Owner's Manual' and for charger maintainer and to fully charge the battery and the maintainer will then keep it topped up. A good quality 4amp (that's all you need) example is available from Lidl for £15. Alternatively you (or someone else) could disconnect the battery following the instructions in the car's 'Owner's Manual', check what might (not all things they list are always effected) need resetting after reconnection, normally if you fully close all windows and sunroof, you only need to reset time-of-day clock, petrol/mileage, seats. Running the car will charge the battery but of course you need to have the electric consumption lower to get more charge back, air-con, heated anything, lights all off, don't turn steering wheel, start/stop off and then unless you leave the engine running long enough to get the oil (not coolant) temperature to 90C+ it won't be best for engine oil or engine. You may get away with leaving the battery 4 weeks, or a lot more perhaps (if not a 2024/5 car) but if the battery gets too low, even if the engine starts, the battery may not fully recover from this if it gets too low and shorten its reliable useful life. Not to turn up the misery but if the 4 weeks extends the need for recharging increases. As always each to their own. HTH.