Places to stay:

Budget:
Stay Okay
https://www.stayokay.com/nl/hostel/utrecht-bunnik?utm_source=GMBlisting&utm_medium=organic
Very close by ceromany and less than 30 minute walk from tolhuys.

Bunk
https://wearebunk.com/utrecht/
Extremely Central in Utrecht

Camping (boomgaard)
https://www.buitengoeddeboomgaard.nl/
Has parking
Bunnik

Hotels:

Moxy
https://www.marriott.com/en-us/hotels/amsou-moxy-utrecht/overview/?scid=f2ae0541-1279-4f24-b197-a979c79310b0
Utrecht Centre (South)

Muze
https://www.muzehotelutrecht.com/?utm_source=GMBlisting&utm_medium=organic
Utrecht Centre (South)

Postillion
https://postillionhotels.com/utrecht/
Has parking
Bunnik

Apartments/lodges

Waterlinie Lodges
https://www.waterlinielodges.nl/
25 minute walk from tolhuys

Boomgaard
https://www.buitengoeddeboomgaard.nl/
Has parking
Bunnik

Bed and Breakfasts

B&B De Mast bij Fort Vechten
https://bb-demast.nl/

Larger group houses:

Bronhoeve
https://www.bronhoeve.com/debron
20 minutes drive from fort bij Rijnauwen
Sleeps up to 14 people
Nature house
Public transport possible with 20minute walk from 341 bus

De Boerenstee
https://www.boerenstee.nl/
Woedenberg
3 accomodations up to 36 people
30 minute drive from Tolhuys

Hogenboom Logies
https://www.hoogenboomlogies.nl/nl/accommodaties
Accomodation and apartment up to 14 people
Montfoort
25 minute drive from Tolhuys

Note: please check if bedding is included in larger group houses in the Netherlands, often there is an extra fee for sheets and towels and sometimes it is not included at all.