Visit my parents abroad not seen since 2017 on ESA IR & PIP

I wanted to ask if I have to actually tell DWP if I want to go and recuperate from surgery at my parents who live in Spain and I haven't visited, or seen them since 2017, over 6years and looking to go for a month as they too are having health issues in their 80s and lots of hospital appointments. If my parents lived in UK I could visit and recuperate with them no problem I take it but because they live in Spain and have for over 21 years then this is a holiday even though it isn't as 1) i'm staying with my parents and 2) I used to live in Spain with my ex-husband too for many years, 15yrs+ ago so its going back to where I used to live as well so very much not a holiday. And not seeing my parents for 6.5years as they haven't travelled back to the UK since 2012 either.
I am on PIP and ESA(IR), EDP, SDP. I read PIP allows up to 12 weeks but ESA 4wks. My question is do you have to actually tell them if going away for a few weeks at all? how do they know, is it linked to HMRC and Passport control. I live alone and have just lost my elderly cat and am heartbroken, alone and had cervical spinal neck surgery last month and recuperating at home alone, but really need to see my elderly parents and mum wants to look after me as her youngest as well, even though I'm 51 and they're 81/82 yrs old. I have no family in the UK so not support as my sister moved to NZ 19yrs ago.
Many thanks
Jacque