Agents’ rights to compensation or (as appropriate, and instead:-) an indemnity cannot be ‘derogated from’ to the detriment of the commercial agent before expiry of the agency contract – this is what Reg 19 of the Commercial Agents (Council Directive) Regulations 1993 provides.
In other words, if an agent has agreed prior to termination that they will accept (in consequence of the agency terminating, in circumstances which give rise to an entitlement under Reg. 17) an amount of money (or a formula for calculating an amount of money) by way of compensation/an indemnity which would result in them receiving a sum which is less than they would otherwise have been entitled to, what was so agreed is void.
Whilst agents may take some comfort from Reg. 19, they need at the same time to be aware that if they ultimately accept, however, as a full and final settlement AFTER termination, any sum which is indeed less than they would otherwise have been entitled to, they would not then be able to rely on Reg. 19 after that point.