Can anybody please help - we have an old stone cottage and the advice I've been getting for internal insulation is leaving us quite confused as to the least risky/most effective method.

- We have 2 feet thick external stone walls with rubble infill . These are facing seaward and are elevated, so they are fairly exposed on the south and west sides only.
- I've removed all the painted cement render from the outside and the intention is to rake out and re-point in (NHL 3 ?) lime as meticulously as possible to reduce air permeability but not vapour perm.

My confusion comes with what to do with the inside in order to keep my insulation level as high as possible and the draughts as low as possible (assuming we can properly draughtproof windows etc). After lots of reading and talking to various 'experts' (none of whom seem to agree) I have distilled my understanding to four possible methods but I'm not sure if my understanding of the actual risks of each one is correct or whether I may be missing another, better method.

Regardless of which method I ultimately use, I intend to repoint the exterior in lime. The four internal options are then :

1. Repoint the interior in lime mortar only. This will give the least insulation internally. This is the only option that will show off the stone walls (not important to us for these walls)
2. Use a hempcrete plaster. Not sure whether this will give decent insulation and not sure how electric fix will work with this.
3. Use tannalised batons fixed directly to the stone with carbon fixings. Insulation with Thermafleece and then Celonit/Building boards on top with lime plaster finish. Maintains breathability but the crooked nature of the walls will probably require cross- batons. Also the direct contact of stone walls with sheepswool insulation ??
4. Fix a timber frame (e.f 4x2) to the floor/ceiling internally but not touching the stone walls so we leave an air gap. Thermafleece insulation and then faced with Celonit / Building boards which are then lime skimmed. Not sure what effect the air gap will have - I'm assuming we seal all other draughts.
5. Other .....

Thanks !!