It's a difficult one.
I agree with Dermot's general suggestion, that as a new business(?), you should focus on keeping cash available to fund the business. If your business outgrows the premises, it is relatively easy to move from a rented premises. It would be a lot more difficult to move from a property you own.
While you may not get the chance to buy this particular premises again, you may be able to buy another premises when you are better off financially.
If this premises is going to be your long term home, buying it may well make sense. If you buy it before the end of this year, you will be exempt from CGT if you hold it for 7 years, so that would argue for going ahead with it, if at all possible.
The only way I can see you doing it is if you sell your home and realise the positive equity in it and use that towards the deposit. When you build up cash again, you will be able to buy another home. I am not recommending this, just suggesting it as a way to achieve what you want to achieve.
If you know anyone who is interested in property investment, they might buy your home from you and rent it back to you, so it won't be too disruptive.
Come to think of it, if you know a property investor, they could buy your business premises with a view to selling them back to you when you can afford to buy them. However, most buyers of investment properties now, want to hold onto them for 7 years to avail of the CGT exemption.