From a Royal Mail press release:

Stamp Issue Date: Tuesday, 16th October 2018 (Stamps and Miniature Sheet)

The Harry Potter series remains to be one of the most beloved and enduring franchises with fans worldwide. The new stamps feature some of the most iconic characters from the films including: Harry; Hermione; Ron; Ginny Weasley and Neville Longbottom.

Product Range at a Glance:

• Set of ten Special Stamps AS4123 £6.70 16th October
• Full sheet of 50 x 1st Class Stamps £33.50 16th October
• Full sheet of 50 x 1st Class Stamps £33.50 16th October
• Full sheet of 25 x 1st Class Stamps £16.75 16th October
• Full sheet of 25 x 1st Class Stamps £16.75 16th October
• Miniature Sheet MZ134 £3.35 16th October
• Special Stamps First Day Cover AF439 £8.60 16th October
• Miniature Sheet First Day Cover MF132 £4.60 16th October
• Prestige Stamp Book First Day Cover HF084 £5.12 4th December
• Special Stamps First Day Envelope AE394 £0.30 16th October
• Miniature Sheet First Day Envelope ME129 £0.30 16th October
• Prestige Stamp Book First Day Envelope HE076 £0.30 16th October
• Stamp Souvenir AW085 £8.60 16th October
• Stamp Sheet Souvenir AW086 £4.60 16th October
• Presentation Pack AP452 £10.75 16th October
• Press Sheet (limited edition of 300) PZ036 £44.49 16th October
• Limited Edition Prestige Stamp Book YB080 £75.00 4th December
• Character Set
• Prestige Stamp Book YB079 £15.50 4th December
• Set of sixteen Postcards AQ269 £7.20 16th October
• Retail Stamp Book UB418 £4.02 16th October
• Collector Sheet AT104 £7.70 16th October
• Hogwarts Medal Cover AM058 £19.95 4th December
• Diagon Alley Medal Cover AM060 £19.95 4th December
• Silver Proof Hogwarts Medal Cover AM061 £99.99 4th December
• Silver Proof Diagon Alley Medal Cover AM059 £99.99 4th December
• Framed Stamp Set N3153 £39.99 16th October
• Framed Collector Sheet N3154 £39.99 16th October
• Framed Miniature Sheet N3155 £39.99 16th October
• Souvenir Art Folder £24.99 16th October
• Stamp Mount 16th October
• Bundle 16th October

Technical Details:

Number of stamps: Ten
Value of Stamps: 1st Class
Design: True North; digital image enhancement: Smoke & Mirrors London
Acknowledgements: HARRY POTTER characters, names and related indicia are © & ™ Warner Bros. Entertainment Inc. (s18)
Stamp Format: Landscape
Stamp Size: 37mm x 35mm
Number per sheet: 25/50
Printer : International Security Printers
Print Process: Lithography
Perforations: 14 x 14.5
Phosphor: Bars as appropriate
Gum: PVA

Mini-Sheet Details:Please note that the Miniature Sheet will be self adhesive rather than gummed (our Miniature Sheets are normally gummed). (The reverse of the minisheet:)

Number of stamps: Five
Design: The Chase
Miniature sheet size: 192mm x 74mm
Stamp Format: Portrait
Stamp Size: 27mm x 37mm
Acknowledgments: HARRY POTTER characters, names and related indicia are © & ™ Warner Bros. Entertainment Inc.
WB SHIELD: © & ™ WBEI. WIZARDING WORLD trademark and logo © & ™ Warner Bros. Entertainment Inc. Publishing rights © JKR. (s18).
Printer : International Security Printers
Print Process:
Perforations: 14 x 14
Phosphor: Bars as appropriate
Gum: Self Adhesive