Signing a new lease on a retail space - apparently I need a solicitor?

Hey, as the title states! The landlord is going to send out heads of terms and provide a lease document for me to sign. They’ve said I need to instruct solicitors, honestly, I’m wondering if I really need this? Any experience / confirmation on this process would be great please!

Also the cost?! Wild! How much should this normally cost for a straightforward lease?

Thanks a lot :)