Here’s the aerial

Without planning permission you are limited to a 1m high fence adjoining a highway. But given you already have the retaining wall, even that may not be possible. I'd suggest contacting the planning department at your local council to get an idea of what might be permitted.

Hi there Ali,
Sarah is right about the 1m height fencing restriction in a front garden adjoining a road. 
If you want privacy, the way to do it would be with planting, and hedging is the best way to guarantee the most privacy that you can get.
If you go for something like a well chosen bamboo species you could get enough height without having to give up a lot of the area that you have. Just please be mindful to plant bamboo inside barriers as they spread uncontrolably otherwise and you will have problems - potential legal disputes with your neighbours - I have seen this happening more than once!
If you would like professional help with your garden, please have a look at my website to see the online services that I provide (from simple budget friendly sketch to full on garden plan with planting scheme) and portfolio. I would be very happy to help you with this!
www.therootedconceptgardendesign.co.uk 

All the best,
Deborah
deborahbiasoli@gmail.com

Thanks for the comments,will contact planning. Was looking at grisilinea for hedging but need something sorted quickly and established size hedge is astronomical pricewise 🙈