hell @J114 , as @stt106 rightly said you can do it yourself. dead easy. i guess where you needed guidance is drawing up the declaration.
£700 is way way too expensive in my opinion. When I wanted to do mine about 2 years, i was quoted around £500. I refused. I went to download some templates online. wrote the declaration. Submitted it along a completed form17. Didn’t hear back from HMRC. 10 months later i got a later that the declaration was rejected. I rang to ask why, I was told the declaration needed to be witness - a witness signature was required.
luckily it was my first year as a landlord, i made a loss that year and there was no tax liability on my part and my Mrs.
i searched online again and found a guy who claimed to have used his declaration template for decades. I bought the template from him for a fraction - word document. not different from what i initially wrote but used his anyway. I filled it out and got someone to sign in the witness section. Submitted it to HMRC along a new completed form17. It was accepted, not issues
if you want, you can send me a private message. i am willing to pass it on to you for £30 with instructions on filling form 17 etc