Sorry to hear business has been slow, I guess it's a difficult time of year as well for outside projects.
I am now your 100th follower on Instagram - but unfortunately nowhere near Billericay
I hope the rugby club job comes off!
Sending your daughter to private school to find clients is certainly a bold marketing strategy
but in all seriousness, I would get as many new friends of hers and parents round to your house as quickly as possible so they see your garden room and word can spread.
I agree with
@thetyreman plan above & that social media advertising is not necessarily great but social media engagement is key! (Check out Derek Barrett Design (fitted furniture) on insta and a podcast he did (trade legends) where he talks about how Instagram has built his business.
Have you joined local facebook groups? I get all my recommendations for trades through a local FB group/page as do many others. I just checked and Billericay Discussion group has 40k members and allows one business post / week.
I looked at your Instagram page and there's nothing obvious to locate it into Billericay / Essex. Can you rename to lawnroomsessex or lawnroomsbillericay.
Your instagram follows look more like the pages you're interested in rather than ones your customers would be. I would start with every local coffee shop / village coffee shop / farm shop and start getting a coffee/pastry from there. Then you post an insta story with them tagged, the coffee cup / pastry in front of your mitre saw 'xyz coffee shop recharging me on my break' etc
They will hopefully reshare it on their page and your target audience (insta housewives) are definitely the type of people who are going to be following coffee shops / farm shops and see that post and might build your following a little bit with local people.
I would definitely check with this company you're working for if you can post stories / pictures on your page for this garden room you're building. Easy to brand it as "Building this garden room for xyz landscapers"
Have you also thought of other outside building projects? A big trend for gardens is outdoor kitchens / bars! I would love a custom, made to measure outdoor kitchen to suit my BBQ etc. I would also say that the market for outdoor kitchens is even bigger than garden rooms. Easier + quicker to build and probably can be just as profitable. Smaller jobs would also be great fillers around bigger ones. Plus you know you can do decking + pergolas easy enough
Do you know anyone who got a green egg or pizza oven for Christmas? A smart stand / cabinet for one of those would be a quick build and if you can get a them as a testimonial etc. Particular people who use social media and will share it on their Insta / FB
Just some ideas which may or may not be helpful!