As a freelance developer, I wasn't VAT registered for the first few years and was in a similar situation - low expenses and most clients were VAT registered.
I didn't encounter any negativity/obstacles with clients, and being VAT registered is extra hassle - VAT 3 returns, an annual RTD return, being aware of how much of your bank balance is VAT due etc.
Also, if there is the possibility of doing work for individuals or small sole traders who are not VAT registered, rates including VAT will be more expensive for them.
However, VAT registered or not, I would always recommend issuing invoices for work done and keeping proper records etc. Emailing invoices is fine, and any proper business would want an invoice before they pay you.