Building regs compliance question

Hello, looking for advice on whether I need to comply with 'proposed' and 'advisory' flood mitigation treatments in building a one storey side extension please. 
We applied to extend out to the side for a kitchen/diner. The house has been extended in the past 25 years with no planning conditions. 
The planning dept wrote to my architect and said 'i note that the property is in an area at risk from surface flooding. Can you provide floor levels and any proposed mitigation' 
My architect sent (without consultation) a response listing a number of 'advisory' actions. These included; 
Using limestone plaster - that's ok 
Sockets above 45cm - that's ok 
No concrete screed above insulation - this one isn't ok because we told him we wanted underfloor heating, and we have a concrete floor. 
Kitchen units to be wooden rather than particle / mdf - again not ok because this would add considerable cost. 
There are others but you get the gist. 
Planning permission was granted and there's no mention of any conditions relating to these proposals. 
The question is - do i need to comply with all of these or can I ignore them since they're just proposals? 
Any advice appreciated before I start talking to builders. 
Thanks

You could add a fully drain around the extension 

Very small cost involved 

That looks brilliant Gary....

That drainage does look very neat, I like it. Are they likely to take that into consideration against the other more extreme proposals then? Thanks

Flood risk is covered by planning consent, not building regulations.

 

On your planning consent there may have been a condition stating that the work will be carried out according to the plans and details submitted.  It is this that would bind you to do as proposed.  If you want to change it you should go back to the planners.  If there is no condition you do not need to worry.

Mr Punter - thanks.

The permission letter says "...carried out in accordance with drawing No. Proposed Plans and Elevations 03A submitted under cover of agents letter dated received by the LPA 22/10/2019.."

 

The letter they refer to is an email from the architect giving floor levels and attaching the mitigation proposals. He describes them as "advisory mitigation measures added".

 

I'm not sure whether the fact that they say "under cover of agents letter" makes those proposals part of a condition?