I wanted to be able to check voicemails or receive calls with work.
This is where you are going to get hit in the pocket. There are all sorts of work arounds for data, and data based calls (like WhatsApp). I've used a dedicated mobile-data router with a Wifi antenna on it that you can use with a local sim to provide hotspots wherever you are.
But if you need to receive old-school phone calls (not WhatsApp) on your existing number, and also use that number to check your 3 Voicemail, I don't know how you can avoid paying €2.02 a minute to listen to your clients, and probably €2.80 per minute to call and listen to your voicemail.
You could try and setup call forwarding for voice mails to a local SIM based number, but I can't predict the cost of this: it will basically be 3's rate for calling Morocco, which I'm guessing is not cheap either.
Short answer: can you convince your clients to call you on WhatsApp only? If so, a data roaming box (cheap enough) and a local SIM will work. A wifi/4g routing box will cost between €20 and €50 depending on the sophistication you like from it, and can be re-used on other holidays. The local SIM will be cheap and cheerful - just make sure it has coverage in your area. You can buy ahead of the holiday from a dedicated international roaming operator, but these costs are pretty high compared to local deals (think €50 per month of service, vs whatever Morocco's got going on). I suspect local deals from shops in the city centre will be better than deals in the airport arrivals lounge, if past experience is any guide. You will need your ID to get a SIM, and they usually want proof of local address.