It may still be worth contacting the school, to see if they can help you by supplying extra training time at the school site, or encouraging teachers to become involved in running a satellite club to your club and getting qualified to coach gymnastics.
Make sure that your development plan is relevant to your club and the situation you are currently facing. As some of your development objectives are met it may be appropriate to change and update them.
You may feel it appropriate to involve parents, as they have a wealth of skills and experience to add to the club, creating more stable, long-term sustainability. Roles could include promotion tasks, legal advice, stewarding at events/competitions, event organisation etc.
However, if your club runs as a business with paid professional staff, you may not need the extra pair of hands. Ensure that your development plan fits the needs and aspirations of your club and only involve parents/guardians if they have a role to play.
Yes, even though you operate as one club, it is your duty to ensure that every piece of equipment used by the club, regardless of where it is stored or used, is checked and safe for use. There may be differing circumstances and procedures depending on the type of the facilities your club uses. Please check with the manager of each facility.