Bungalow - second storey and permitted build guidelines help please (side and rear extension)

[Alice Nicholls]

Hi, in need of some advice please? We have a bungalow and we are going to apply for planning to go up a storey. Next door is a house the other side a bungalow. 
 

However, our original plans were to build an annex on the side on the house, knocking down the garage to achieve this, so we could live in the annex whilst we built the second floor. Is there any way to do this on permitted build please? We’ve had an architect (not our architect) say he thinks we could do this on PB? But I’m concerned as it’s technically altering out house as there is a demolition of a garage to consider. 
 

We also want to do PB 4m out the back (eventually not on plans). I’ve seen online guidance we can do the two but they can’t be touching? (But obviously it also not clear on the garage issue). I feel this is such a grey area and I understand we have to be under a certain height, but what would the length of PB side annex be? And can we do it with the garage being there? Any advice welcome, plans attached and second floor plan for dims. Thank you kindly! 

Edited March 5 by Alice Nicholls
Added drawing